sliding bearings

Hello all

Been a member on here few years now , not posted much for a long while, few years I recon, please dont feel like i only want to talk to you all, is only when I need something.

I have this project, building longer rails on a chop saw, I have the rails, they are 25mm hardened steel shafts, I was thinking on using bronze bearings, but found some mild steel thick wall ferruls 50mm long 40mm od exact slide fit 25mm id

Will these mild steel ferulls/bearings be ok for wear on a hardened steel shaft

lee

Hello Lee,

You would do better with cast iron, it is a recognised bearing material for steels hard and soft and provides it's own lubrication with the carbon content, a nice bonus to avoid grinding bearings/shaft with oil bound dust from the sawing

Regards

Brian

Hi Lee, If the new parts allow a good sliding fit I would go with them but use a silicone spray lubricant.

When they become too worn for the accuracy required you can bore them out and fit bushes to suit.

Emgee

Linear (spelling?) bearings are cheap and having multiple ball bearing glide really easy. Use your mild steel until they wear out, I guess it will be a long time.

I would use proprietary bearings from either Oilite (impregnated bronze) or Igus (engineering plastics). They are both relatively cheap and obtainable.

+1 for Linear Bearings, that's what some of the top chop saw manufacturers use, ideally you should have scraper seals to stop debris getting into the bearings.
I wouldn't use Silicone Oil on anything with metal to metal sliding components, it's unsuitable, Silicone Oil is great for metal to plastic and plastic to plastic though.

- Nick

Nick, check this out for the difference between "silicone oil" and "silicone spray lubricant"

**LINK**

Emgee

It's still Silicone though be it in oil, spray or grease form which as stated isn't really for metal to metal contact no matter what the advertising blurb says.

Mick, I have used the silicone spray lubricant without problems on machine slides, after spraying it dries off and leaves a slippery surface coating on metals.
I have also used silicone oil, the manufacturer's recommended lubricant for fan bearings working in high temp situations.

Emgee

Just to add fuel to the silicone oil 'fire', it has long been a bone of contention in airgun circles - after a lot of reading the pros and cons, I now only use moly-based grease for mine. A pretty good explanation can be found on this page **LINK**

Regards,

Rob

Thanks everyone for your ideas

I am no professional engineer, but do like to do things that make a proper job, So I have opted for the oilite bronze bush, these here http://www.ashleypower.co.uk/store.php/products/amc253550-metric-plain-oilite-bush

Ive been having a study of these bushes, what I have learnt , is that these bushes need to be pressed in so as to close them down to get them to fit the shaft, so when you order them at what I need 25mm id , they are a fraction over that size Is this correct ?

Thanks

Lee

Lee,

May I refer you to this thread: **LINK**

http://www.model-engineer.co.uk/forums/postings.asp?th=124276

I think you should find all the Oilite information that you need.

MichaelG.

Thanks MichaelG

Will do.

I think I would try Oilite sintered iron bushes in this situation, they work the same way as the bronze Oilite bushes.

Ian S C

Ian,

Iron Bushes, only place I can find these are from companies located in India, do you know Where i could buy these in the UK

or what about these  https://www.bearingboys.co.uk/BU-Type-Bearings/MB2550BU-Split-Bearing-Bush-14894-p

Thank

lee

Edited By lee hawkins 1 on 03/03/2018 12:54:22

Edited By lee hawkins 1 on 03/03/2018 13:13:22

Sorry Lee, I'm at the other end of Earth, in NZ.

Ian S C

Ha ha no worries Ian

Thanks

lee